Slider loading mechanism

ABSTRACT

The present invention relates to a flexible slider-loading mechanism for an optical drive with interchangeable optical storage media. A slider-loading mechanism according to the invention for an optical drive, having a slider which is fastened on a resilient arm and is lowered onto the surface of an optical storage medium and/or raised from the surface of the optical storage medium, is characterized in that a loading element which is not connected to the resilient arm is provided, the loading element acting on the resilient arm and causing the slider to be lowered and/or raised.

The present invention relates to a flexible slider-loading mechanism foran optical drive with interchangeable optical storage media.

In hard-disk technology, use is made of writing/reading heads, referredto hereinbelow as sliders, which are shaped like missiles and float on athin air cushion above the storage disks of the hard disk. The aircushion here is produced by the rapid rotation of the hard disk. Theslider is fastened at the end of a resilient arm and is moved, by way ofthe latter, to the respective writing/reading positions of the harddisk. The air cushion breaks up if the rotational speed of the hard diskdecreases or if the hard disk comes to a standstill, and/or it has to bebuilt up in the first instance when the hard disk starts up. There isthus a special start/stop procedure for these cases, by means of whichthe slider is applied to the storage disk (loaded) and/or removedtherefrom, in order to avoid damage to the storage disk and the slider.Essentially two possibilities are known for the start/stop procedure ofthe slider:

1.) A special landing zone on the storage disk: there is a parkingposition on a specifically roughened region of the storage disk. Thedata region on the storage disk has a very smooth surface. If the sliderwere to land there, it would be torn off from the resilient arm byadhesive forces as soon as the hard disk starts up.

2.) Rampload mechanism: an appropriate mechanism moves the slider fromthe storage-disk surface, via a ramp, into a parking position outsidethe outer periphery of the storage disk. This method is problematic ifthe storage disk has excessive vertical wobble on the outer periphery,since loading can only take place on the outside.

Both of the abovementioned methods are unsuitable for testing systemsand other systems with interchangeable storage disks (e.g. opticalstorage means) since loading cannot take place at all locations of thestorage disk and moreover, in case 1, there is no decoupling from thestorage disk. Various possibilities have thus been developed for testingsystems, and these are illustrated in FIG. 1.

The methods which are shown in FIG. 1 have the disadvantage that theslider is guided up onto the storage disk in an undefined ornon-parallel manner and the suspension of the resilient arm has to bemoved. This adversely affects the reproducibility of the resilient-armposition.

The article entitled “Effective Design and Performance of an OpticalFlying Head for Near-Field Recording”, Jpn. J. Appl. Phys. Vol. 41(2002), pp. 1884-1888 by Kim et al. discloses attempts to transfer thedisplacement of the slider sliding on an air cushion, this being knownfrom hard disks, to optical drives with interchangeable optical storagemedia. The slider may bear, for example, a magnetic coil and/or anobjective lens with a high numerical aperture or a part thereof (e.g. aso-called Solid Immersion Lens, SIL), which can thus be moved, on theoptical axis, to a very small operating distance from the opticalstorage medium. The slider is arranged on an optical writing/readingdevice which can be displaced relative to the optical storage medium.Since the use of a landing zone is ruled out if interchangeable opticalmedia are used, the construction which is presented in the documentmakes use of a resilient arm, miniature optics being integrated in apivoting arm of the resilient-arm fastening. The rampload mechanism isrealized in accordance with a mechanism which is known from hard-disktechnology. Loading is thus only possible on the outer periphery of thestorage medium. In the case of cost-effective storage media made ofplastic—in contrast to hard disks—deviations from the ideal disk plane(vertical wobble or axial runout) are usually found on the outerperiphery, and these render loading on the outer periphery moredifficult or even impossible. This requires a special loading mechanismwhich can operate on the inner periphery of the storage region or at anyother desired location and can decouple the slider from the storage diskaltogether.

It is an object of the invention to improve the solution which is knownfrom the prior art.

According to the invention, this is achieved by a slider-loadingmechanism for an optical drive, having a slider which is fastened on aresilient arm and is lowered onto the surface of an optical storagemedium and/or raised from the surface of the optical storage medium, aloading element which is not connected to the resilient arm beingprovided, and the loading element acting on the resilient arm andcausing the slider to be lowered and/or raised. In the lowered position,the resilient arm is not in contact with the loading element, with theresult that the slider slides over the surface of the storage mediumwithout being influenced. In the raised position, the resilient arm isdeflected slightly from the surface of the storage medium by the loadingelement. In this way, the fastening point of the resilient arm is fixed,with the result that the resilient arm, and thus also the slider, isalways oriented in the same way in relation to the optical axis in thelowered position. It is additionally possible, however, to provide avertical adjusting means for adjusting the prestressing of the resilientarm and thus the resilient force which acts on the slider. On account ofthe changeover between two stable states, namely the slider lowered orthe slider raised, there are no undefined intermediate positions.

The loading element advantageously penetrates between the surface of theoptical storage medium and the resilient arm. This easily allows theloading element to act on the resilient arm without there being any needfor high-outlay mechanisms for force-transmission purposes.

The loading element is preferably actuated via a lever. By virtue of anindirect lever mechanism, the slider is raised off from the surface ofthe storage medium by only a few tenths of a millimeter. The slider isthus set down on the surface of the storage medium and/or raised fromthe surface, as far as possible, parallel thereto.

According to the invention, the lever is actuated via a gear mechanism.Well-defined and reproducible actuation of the lever is achieved in thisway. The gear mechanism preferably has a loading pin which is providedwith a gearwheel and is screwed into the writing/reading device. Byvirtue of the rotation of the gearwheel, the loading pin is screwed intothe writing/reading device and/or unscrewed therefrom. The movement ofthe loading pin then serves for actuating the lever.

The gear mechanism advantageously has a rack. By virtue of this rackbeing fastened on the optical drive outside the displaceablewriting/reading device, it is possible to dispense with an additionalmotor drive for the loading function. The loading operation then takesplace, for example, via the rough tracking function of thewriting/reading device, this giving rise to a relative movement betweenthe rack and the loading pin screwed into the writing/reading device.The speed of the loading operation can be adjusted via variable roughtracking advancement. It is, of course, also possible to provide aseparate motor drive for the loading operation.

A further advantage can be achieved by the rack being arranged in adisplaceable manner. In this way, a loading operation is possible atvirtually any desired location of the storage medium. It is sufficient,for this purpose, to displace the rack to the desired position. It isnevertheless possible to move to a stable parking position outside thestorage medium for changing over the medium.

It is further advantageous to provide a linear drive for the rack, whichmakes the loading operation possible even when the writing/readingdevice is at a standstill. This also allows the slider to be set down inthe outermost region of the storage medium, which is otherwise verydifficult to achieve. At the same time, it is thus possible to skipdefective regions of a storage medium and to use storage media withdifferent diameters. In the event of any possible faults, the slider canbe raised off from the storage medium at any desired location; standbyoperation is also possible in any position. If the slider is set downdirectly in the written disk region, this does not adversely affect thenot yet written regions on the storage medium.

According to a further aspect of the invention, the lever is actuatedvia a cam control means. Well-defined and reproducible actuation of thelever is thus achieved in a straightforward manner. The cam which isrequired for the cam control means here is fixed on the opticalwriting/reading device, while the lever is arranged outside thereading/writing region of the optical storage medium. This allows theslider to be set down and/or raised only on the periphery of the storagemedium. However, the converse arrangement is also possible, i.e. the camis arranged outside the reading/writing region of the optical storagemedium, while the lever is fixed on the optical writing/reading device.Both arrangements can easily be integrated in existing designs ofoptical writing/reading devices.

A slider-loading mechanism according to the invention is advantageouslyused in an apparatus for reading from and/or writing to opticalrecording media. Using a slider in such an apparatus makes it possibleto realize recording mechanisms which utilize optical near-field effectsor the magnetooptical recording with an objective-side coil. This isnecessary, for example, if use is made of a high numerical aperture andthin substrate and/or covering layer. It is thus possible to achieverelatively high density of data on the storage media.

To aid understanding, the invention will be explained hereinbelow withreference to FIGS. 1 to 4. The same designations designate the sameelements. In the figures:

FIG. 1: shows loading mechanisms in testing devices for storage mediawith sliders according to the prior art;

FIG. 2: shows a loading mechanism according to the invention for opticaldrives;

FIG. 3: shows a variant of the loading mechanism for a testing system;and

FIG. 4: shows a further exemplary embodiment of a loading mechanismaccording to the invention.

FIG. 1 shows various possible ways of realizing the loading mechanism inthe region of testing devices for storage media as are known from theprior art:

a) Tilting Loading Lever:

The point of rotation of the loading mechanism is located at the end ofthe resilient arm (6). The resilient-arm suspension (9) is a type ofdirect lever mechanism. The loading operation can thus only take placein the outer regions of the storage medium (8) without causingcollisions with the storage medium (8).

b) Loading Lever:

The point of rotation (11) of the loading mechanism is located at theend of the resilient-arm suspension (9). The loading operation is thuspossible at any desired location of the storage medium (8), but theslider (2) is not guided up parallel to the surface of the storagemedium (8). This means that the slider (2) approaches the surface, inthe first instance, with an outer edge. This increases the risk of theslider (2) being able to collide with the storage medium (8) before thebuild-up of the air cushion for stable flight of the slider (2).

c) Loading Lever with Loading Finger:

During the loading operation, the slider (2) is retained in a virtuallyhorizontal position by support of the resilient arm (6) with a loadingfinger (12). The slider (2) is thus guided up onto the surface of thestorage medium (8) in a more or less parallel manner.

FIG. 2 shows a loading mechanism according to the invention for anoptical drive. During operation, with the storage medium (8), which isonly shown in part here, rotating, the slider (2) flies on an aircushion approximately 20 nm to 1.5 μm above the surface of the storagemedium and is retained in a vertically flexible manner by a resilientarm (6) with defined spring characteristics. For the abovementionedreasons relating to adhesive forces, the slider (2) must not be set downon the surface of the storage medium (8) when the latter is at astandstill. A mechanical loading mechanism, which sets down the slider(2) gently when the storage medium (8) is rotating, is thus required.This allows the air cushion to build up before contact with the surfaceof the storage medium (8) can take place. The slider (2) iscorrespondingly raised off from the rotating storage medium (8).

The loading mechanism which is shown in FIG. 2 does not require anadditional drive since the lever mechanism is actuated via themotor-driven rough tracking function which is provided as standard inthe writing/reading device (4). A loading tip (1) penetrates between thesurface of the storage medium (8) and the resilient arm (6). Thisloading tip is mounted on a loading lever (3) which, by way of a definedtilting movement, raises and/or lowers the resilient arm (6) and thusthe slider (2). The loading tip (1) makes a displacement ofapproximately 0.3 mm at the location where force is introduced into theresilient arm (6), of which approximately 0.1 mm is idle displacementuntil contact is first made with the resilient arm (6). This results ina displacement in the center of the slider (2) of approximately 0.3 mm.The loading lever (3) is actuated by the loading pin (7), which isprovided with a gearwheel and is screwed into the writing/reading device(4). The rotation of the loading pin (7) in the thread of thewriting/reading device (4) results in a vertical movement upward ordownward, depending on the direction of rotation. The defined rotationof the loading pin (7) is realized via a rack (5), which is fitted in adisplaceable manner on the frame and of which the number of teeth iscoordinated with the leverages of the system and the thread pitch of theloading pin (7). Using the tracking motor provided, depending on thedirection of travel, by engagement of the rack (5) at the predefinedlocation, the loading pin (7) is raised or lowered. An appropriateselection of the thread direction and displacement stops for the rack(5) ensure that the slider (2) is always lowered and/or raised in thereading/writing region of the storage medium (8). If the slider (2) isset down, via the loading mechanism, at any desired location on thestorage medium (8), rather than on the outer periphery of the storagemedium (8), and if the skipped peripheral regions of the storage medium(8) are nevertheless to be read out/written to, the rack (5) then has tobe pushed onto the end stop corresponding to the outer periphery of thestorage medium (8). Otherwise, the loading mechanism would raise theslider (2) again at the location at which it has set it down. Themovement of the writing/reading device (4) in the direction of thecenter point of the storage medium (8) causes the slider (2) to belowered onto the surface of the storage medium (8). The movement of thewriting/reading device (4) in the direction of the periphery of thestorage medium (8) causes the slider (2) to be raised from the surfaceof the storage medium (8). As an alternative, it is possible to adjustthe desired loading position via a suitable linear drive for the rack(5). It is also possible at the same time in this case to realize theloading operation, with the writing/reading device (4) at a standstill,by the displacement of the rack (5).

FIG. 3 shows a variant of the loading mechanism according to theinvention which can be used, for example, in a testing system. Using aremovable end stop (13) allows the rack (5) to be pushed out of theregion of the storage medium (8) in order that the slider (2) can alsomove to the outermost periphery of the storage medium (8) in order toread from and/or write to the storage medium (8) or to carry out othertests thereon.

A further exemplary embodiment of a loading mechanism according to theinvention is illustrated in FIG. 4. The loading operation here takesplace via a cam control means on the outer periphery of the storagemedium (8). In this case, the loading lever (3) is fixed on the frame ofthe drive. The loading operation for lowering and raising the slider (2)always takes place in the outer region of the optical storage medium(8). A cam (10) mounted on the writing/reading device (4) controls thedeflection of the resilient arm (6) by the loading tip (1) during theloading operation. The movement of the writing/reading device (4) in thedirection of the center point of the storage medium (8) causes theslider (2) to be lowered onto the surface of the storage medium. Themovement of the writing/reading device (4) in the direction of theperiphery of the storage medium (8) causes the slider (2) to be raisedfrom the surface of the storage medium (8).

1. A slider-loading mechanism for an optical drive, having a sliderwhich is fastened on a resilient arm and is lowered onto the surface ofan optical storage medium and/or raised from the surface of the opticalstorage medium and a loading element separate from the resilient arm,the loading element penetrating between the surface of the opticalstorage medium and the resilient arm and being actuated via a lever foracting on the resilient arm to lower and/or raise the slider, whereinthe lever is actuated via a gear mechanism having a loading pin, whichis provided with a gearwheel, and a rack, which is arranged in adisplaceable manner and interacts with the gearwheel of the loading pin.2. The slider-loading mechanism as claimed in claim 1, wherein a lineardrive is provided for the rack.
 3. The slider-loading mechanism asclaimed in claim 2, wherein the gearwheel of the loading pin is actuatedby moving the rack relative to the gearwheel with the linear drive. 4.The slider-loading mechanism as claimed in claim 1, wherein thegearwheel of the loading pin is actuated by moving the gearwheelrelative to the rack using a rough tracking function.
 5. Theslider-loading mechanism as claimed in claim 1, wherein displacementstops for the rack for ensuring that the slider is always lowered and/orraised in a reading/writing region of the storage medium.
 6. Theslider-loading mechanism as claimed in claim 1, wherein in the loweredposition the resilient arm is not in contact with the loading element.7. The slider-loading mechanism as claimed in claim 1, wherein itfurther includes an adjusting means for adjusting the prestressing ofthe resilient arm.
 8. A unit for reading from and/or writing to opticalrecording media, wherein it has a slider-loading mechanism as claimed inclaim 1.